ORGANIZATION AND NUCLEOTIDE-SEQUENCE OF A GENE-CLUSTER COMPRISING THE TRANSLATION ELONGATION FACTOR-1-ALPHA FROM SULFOLOBUS-ACIDOCALDARIUS

The gene encoding elongation factor EF-1-alpha from Sulfolobus acidocaldarius was localised to a 4200 bp EcoRI fragment of plasmid pIN IIIA (Puhler, G. et al., 1989, Nucleic Acids Res. 17, 4517-4534). Sequence analysis of this DNA fragment revealed the existence of the genes for ribosomal protein S7, elongation factor EF-1-alpha, ribosomal protein S10 and transfer RNA(Ser) (GGA). Analysis of transcripts derived from this chromosomal region showed that these genes are co-transcribed. Additional promoters, which are situated within this transcriptional unit, and several sites of putative transcriptional termination or processing were identified. The organisation of the genes is very similar to that of homologous genes comprising the "streptomycin operon" in Methanococcus vannielii and in Bacteria, apart from the fact that the gene for elongation factor EF-2 is not located in this transcriptional unit. A phylogenetic tree based on the comparison of EF-1-alpha/Tu sequences from Archea1, Bacteria and Eucarya supports the concept of the monophyletic origin of the archael kingdom and shows that Archaea have a smaller evolutionary distance to Eucarya than to Bacteria.